Engines generally utilize air filters for removing debris from air supplied to the engines. An engine may experience engine failure if the air filter becomes clogged and insufficient air flow is able to pass through the clogged filter. One method for monitoring clogging, otherwise referred to as “loading,” is by measuring the differential air pressure across the filter. This may be done by providing an air pressure sensor on the upstream side of the filter (i.e., the “dirty side of the filter”) and an air pressure sensor on the downstream side of the filter (i.e., the “clean side of the filter”). The difference in air pressure across the filter as determined by these sensors, or ΔP, may be used to assess loading of the air filter. However, this “two sensor” approach adds cost and complexity to an air filter system. A less expensive and less complex system for monitoring loading of an air filter is desirable.